<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>邮箱选择</title>
    <style>
        /* 样式重置 */
        .mail {
            width: 120px;
            border: 2px solid #999;
            text-align: center;
            display: block;
        }

        .mail:hover ul li {
            display: block;
        }


        .header {
            color: #fff;
            background-color: #000;
        }

        ul {
            list-style: none;
            padding: 0;
            margin: 0;      
        }

        ul li {
            display: none;
        }

        ul li a {
            text-decoration: none;
            color: #000;
            display: block;
        }

        .mail ul li:hover {
            background-color: skyblue;
        }
    </style>
</head>
<body>
    <div class="mail">
        <div class="header">邮箱</div>
        <ul>
            <li><a href="#">QQ邮箱</a></li>
            <li><a href="#">163邮箱</a></li>
            <li><a href="#">foxmail邮箱</a></li>
        </ul>
    </div>
</body>
</html>